In autumn and winter the upper atmosphere cools down quickly as the permanent polar night sets in. (bitsofscience.org)
«The end of polar night also implies that more than half of our stay in Antarctica has passed and that this great experience won't last long anymore.» (sciencemag.org)
Due to the tilt of approximately 27º of the planet Saturn, its polar atmosphere undergoes intense seasonable variations with long polar nights lasting over seven years, followed by a long period of 23 years of variable illumination. (sciencedaily.com)